(57) Water washable substantially biodegradable compositions having excellent sensitivity and high stability, for use in non-destructive testing of objects for contaminant detection and identification. The contaminant identifier composition consists essentially of a fluorescent dye and a suitable carrier. The developer composition consists essentially of an organic dye or combination of dyes, preferably fluorescent dyes, and a carrier or solvent therefore, in the form of certain ethoxylated linear alcohols, particularly the biodegradable nonionic surfactants comprised of ethoxylates of a mixture of secondary alcohols having linear alkyl chains of from 10 to 17 carbon atoms. In the method of application the contaminant identifier is first applied to the surface of an object to be tested to detect the presence of the contaminant. Excess identifier is removed and the developer composition applied for a time sufficient to dye the contaminant. The surface is then flushed to remove any excess developer and, the surface of the object is viewed under suitable light and conditions, eg., ultraviolet or black light to locate surface contaminants.